POC: Cross-team recent search (#20027)

Just a quick POC to move fast :P

We use a search pointer to keep track of
the next row to inesrt to. For every new search
we increment the pointer and do modulo 5.
This means that the value will always remain
between 0-4. And that way, we will always overwrite
the oldest entry on every search.

And while getting the results, we get
all results for that user.

The search parameters are json marshalled
and stored as a JSON blob. This is because
there is no need to search/filter them
in the DB.

Pending items:
Tests obviously.

To improve:
The client needs to send the channel ids
instead of channel names.

app/post.go

@@ -1305,7 +1305,7 @@ func (a *App) SearchPostsInTeam(teamID string, paramsList []*model.SearchParams)
 	})
 }
 
-func (a *App) SearchPostsForUser(c *request.Context, terms string, userID string, teamID string, isOrSearch bool, includeDeletedChannels bool, timeZoneOffset int, page, perPage int) (*model.PostSearchResults, *model.AppError) {
+func (a *App) SearchPostsForUser(c *request.Context, terms string, userID string, teamID string, isOrSearch bool, includeDeletedChannels bool, timeZoneOffset int, page, perPage int, modifier string) (*model.PostSearchResults, *model.AppError) {
 	var postSearchResults *model.PostSearchResults
 	paramsList := model.ParseSearchParams(strings.TrimSpace(terms), timeZoneOffset)
 	includeDeleted := includeDeletedChannels && *a.Config().TeamSettings.ExperimentalViewArchivedChannels
@@ -1317,10 +1317,14 @@ func (a *App) SearchPostsForUser(c *request.Context, terms string, userID string
 	finalParamsList := []*model.SearchParams{}
 
 	for _, params := range paramsList {
+		params.Modifier = modifier
 		params.OrTerms = isOrSearch
 		params.IncludeDeletedChannels = includeDeleted
 		// Don't allow users to search for "*"
 		if params.Terms != "*" {
+			// TODO: we have to send channel ids
+			// from the front-end. Otherwise it's not possible to distinguish
+			// from just the channel name at a cross-team level.
 			// Convert channel names to channel IDs
 			params.InChannels = a.convertChannelNamesToChannelIds(c, params.InChannels, userID, teamID, includeDeletedChannels)
 			params.ExcludedChannels = a.convertChannelNamesToChannelIds(c, params.ExcludedChannels, userID, teamID, includeDeletedChannels)
@@ -1352,6 +1356,15 @@ func (a *App) SearchPostsForUser(c *request.Context, terms string, userID string
 	return postSearchResults, nil
 }
 
+func (a *App) GetRecentSearchesForUser(userID string) ([]*model.SearchParams, *model.AppError) {
+	searchParams, nErr := a.Srv().Store.Post().GetRecentSearchesForUser(userID)
+	if nErr != nil {
+		return nil, model.NewAppError("GetRecentSearchesForUser", "app.recent_searches.app_error", nil, nErr.Error(), http.StatusInternalServerError)
+	}
+
+	return searchParams, nil
+}
+
 func (a *App) GetFileInfosForPostWithMigration(postID string) ([]*model.FileInfo, *model.AppError) {
 
 	pchan := make(chan store.StoreResult, 1)